9 Computational EEG Analysis for Brain-Computer Interfaces
197
9.1.3 Types of EEG Responses for BCI Control
For achieving different modes of control, EEG responses can be further categorized
into transient and continuous responses.
9.1.3.1 Transient
Transient responses are momentary changes in the EEG that can be associated with
a transition of a sensory stimulus (reactive), or a transition in mental imagery or
cognitive state such as a single hand grasp (active). Such transient responses are
well-suited for making discrete selections in applications such as BCI typing.
9.1.3.2 Continuous
Continuous responses represent ongoing EEG activity that differs from resting-state
activity. In reactive paradigms, this is associated with repetitive sensory stimuli that
likewise produce repetitive “steady-state” patterns in the EEG. In active paradigms,
continuous mental imagery or cognitive state entrainment produce sustained changes
in the EEG that, in some cases, can also produce graded modulation with training
to allow more refined control. Such continuous responses are well-suited for continuous dimensional-control applications such as controlling a cursor or a motorized
wheelchair.
9.1.4 Organization of the Chapter
The selection of a processing approach must be guided by the nature of the signals
in consideration. Most BCIs can be classified within the taxonomy of active/reactive
and transient/continuous (see Table 9.1). Within this taxonomy, the conventional
associated EEG analysis techniques are largely unique and distinctive. Thus, this
chapter presents the most fundamental and widely-used EEG analysis techniques
organized by this taxonomy.
9.2 Active Paradigms
The EEG responses associated with common active paradigms generally form distinct spatial patterns within a specific frequency range(s). Thus, techniques that detect
the spatial patterns in frequency bands associated with mental imagery (i.e., μ and β)
are commonly employed for this detection problem. Two fundamental approaches are
197
9.1.3 Types of EEG Responses for BCI Control
For achieving different modes of control, EEG responses can be further categorized
into transient and continuous responses.
9.1.3.1 Transient
Transient responses are momentary changes in the EEG that can be associated with
a transition of a sensory stimulus (reactive), or a transition in mental imagery or
cognitive state such as a single hand grasp (active). Such transient responses are
well-suited for making discrete selections in applications such as BCI typing.
9.1.3.2 Continuous
Continuous responses represent ongoing EEG activity that differs from resting-state
activity. In reactive paradigms, this is associated with repetitive sensory stimuli that
likewise produce repetitive “steady-state” patterns in the EEG. In active paradigms,
continuous mental imagery or cognitive state entrainment produce sustained changes
in the EEG that, in some cases, can also produce graded modulation with training
to allow more refined control. Such continuous responses are well-suited for continuous dimensional-control applications such as controlling a cursor or a motorized
wheelchair.
9.1.4 Organization of the Chapter
The selection of a processing approach must be guided by the nature of the signals
in consideration. Most BCIs can be classified within the taxonomy of active/reactive
and transient/continuous (see Table 9.1). Within this taxonomy, the conventional
associated EEG analysis techniques are largely unique and distinctive. Thus, this
chapter presents the most fundamental and widely-used EEG analysis techniques
organized by this taxonomy.
9.2 Active Paradigms
The EEG responses associated with common active paradigms generally form distinct spatial patterns within a specific frequency range(s). Thus, techniques that detect
the spatial patterns in frequency bands associated with mental imagery (i.e., μ and β)
are commonly employed for this detection problem. Two fundamental approaches are